Author: Ross Boyd
Date: 00:26:09 01/19/06
Go up one level in this thread
On January 18, 2006 at 15:51:42, Uri Blass wrote: >On January 18, 2006 at 15:30:03, Ross Boyd wrote: > >>On January 18, 2006 at 15:05:36, Dann Corbit wrote: >> >>>On January 18, 2006 at 14:39:40, Fernando Villegas wrote: >>> >>>>Some days ago I talked of knowledege to know which knowledge is irrelevant as a >>>>probable feature of Rybka. And almost nobody answered or commented my post. >>>>Surely it is an advantage to be a chess programmer in a site like this. >>> >>>Probably the only one who can answer correctly is the author. >>> >>>But you can look at some interesting generalizations. >>> >>>I have found that some evaluation terms add nothing either to the EPD solution >>>count or the contest point gathering effectiveness of an engine. >>> >>>An example is queen mobility. I don't know of any logical reason why its >>>computation should not help, but it doesn't. >>> >>>I have seen other chess engine authors come to the same conclusion. >> >>Agreed. I do pseudo mobility only for bishops and knights. Queen mobility >>improves nothing. However, I do piece-square so the queen knows about >>centralisation. > >For me it is the opposite about queen. > >I do not have piece square table for centralization of the queen but I have >mobility for all pieces. > >I have piece square table for the queen but it is not about centralization and I >do not know if it is productive(probably I will need a lot of games to test it >because my piece square table only change the value of queen by at most 0.1 pawn >and it does not change the value of queen in most squares). > >Here is my piece square table for the queen(a8 a7 a2 a1 h8 h7 h2 h1 considered >to be relatively bad squares for the queen when h6 a6 considered to be good >squares for the white queen because it may help in mate attacks in these >squares). > >queen_square_table 990 1000 1000 1000 1000 1000 1000 990 990 1000 1000 >1000 1000 1000 1000 990 1010 1000 1000 1000 1000 1000 1000 1010 1000 >1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 >1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 990 1000 1000 1000 >1000 1000 1000 990 990 1000 1000 1000 1000 1000 1000 990 > >Uri Hi Uri, Yes, my queen piece square table has more amplitude than yours but generally I try to avoid tucking the queen into corners where its influence is _usually_ going to be reduced. One other thing though, by raising the value for a6 and h6 you are speculating. For instance, what if the king is castled q side? and you still give a slight bonus when the queen is on h6. Maybe better is some sort of bonus for proximity to the enemy king (which increases when the enemy king is undefended and/or there are other pieces also bearing down on the king). That's what Chrilly is talking about. Its important (if not a little difficult) to ensure you don't give inappropriate bonuses like in the a6/h6 example above. Don't worry I make these mistakes and much worse in TRACE... but its an interesting concept to write an eval that is indeed accurate in the highest possible % of positions. Ross
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